**2. Technical challenges in microgrid**

The challenges related with the control and operations of microgrids are very high. Microgrids are required to ensure the reliable operations even at fault conditions, power system stability during disturbances, and power quality in the island mode. The grid connected microgrid is needed to be maintained synchronism at any situations. Microgrids need to have advanced control strategies for microgrid inverters to maintain correct frequency and voltage to ensure stable operations for the power system connected with dynamically variable load. The growth of microgrids and its challenges has gained attention of researchers and various government and private organizations to play a vital role in finding out the solutions of effective implementation of microgrid. One of the major problems in microgrid is protection system in main grid and microgrid faults. When there is any fault in main grid protection, microgrid needs to be isolated immediately, and similarly if there is any fault in microgrid, the protection system should isolate the smallest part of the microgrid to clear the fault. The selectivity and sensitivity plays a vital role in low voltage microgrid power management. False tripping, unnecessary tripping, delayed tripping, and undetected faults are the major challenges in design of protection system in microgrids. The number of installation of distributed energy resources and availability of short-circuit current in the islanded mode of microgrid are the major issues while considering the protection of microgrids. Compared to main grid, the short-circuit current will drop down drastically and will give problem in the protection of microgrid. There is a need for designing a proper protection system for distributed energy resources with short-circuit calculations and placement of over current relays, reverse power relays, and directional over current relays. In real time, the operating conditions of microgrid are variable because of intermittent distributed sources and dynamic electrical load demand. This leads to change in network topology frequently to aim to minimize loss, economic load dispatch, and proper unit commitment with satisfying all the constraints. The directions and magnitudes of short circuit will vary because of these situations. The different sizing of equipment in various components of microgrid creates often a loss of relay coordination, and generic over current protection will become ineffective in protection of the microgrid from faults. The invention of new methodology in protection mechanism is very much needed to set different parameters for over current protection, parameters of relays, deal with low short circuit current, and interfacing of power electronic devices with the microsources [14].
